You start the mission ducked behind your shuttle for cover. On the other side of the shuttle is a hangar full of Cerberus troops shooting at you. Centurions and Assault Troopers will flank you relatively quickly, so start thinning out their ranks before they can get to you.

Once you get to the other side of the shuttle, there are more troops and an Atlas Mech waiting for you. Be sure to look up -- there is a Nemesis sniping at you from the second level. Both the Atlas and the Nemesis are on the left side of the docking bay, so take cover accordingly. It's easiest to thin out the troops from cover, then take out the Atlas, and save the Nemesis for last. If you can get past those forces though, there are not 1, but 2 empty Atlas Mech's waiting for you on polar ends, just right and left of the fighter platform sitting back.

Note that you could also hijack this Atlas -- it won't give you a major advantage but it's entertaining and worth an Achievement/Trophy.

As soon as you take out the last enemy, you'll hear an announcement about a security breach (that's you!) and that the Achilles Protocol is being initiated. EDI translates for you: they're going to vent the hangar. Even though there's no timer, if you don't get EDI to an active console to stop the venting, you'll be sucked out into space and fail the mission. Quickly climb up the ladder on the left side of the hangar up to where the Nemesis used to be, then go through the door on your right and activate the hangar bay compression controls. This stops the timer.

After the short cut scene, reinforcements will appear on your left. Take them out, then continue down the hallway and cross over to the other side of the hangar on the second level. Halfway across you'll be greeted by the remainder of the welcome party: Assault Troopers, Centurions, and another Nemesis.

Once you're clear, continue to the far end of the catwalk and open the door. In the small room, activate the Rotation Controls to aim the Cerberus fighter inward towards the hangar doors. Behind the controls is a dark room with a Med Kit. Continue through the series of small rooms until you come to the last room.

PDA (Credits) - Go past the ladder and pick this up on the crate next to some ammo.

Turn around and go back one room. Go down the ladder back to the first floor of the hangar. If you need some ammo, you should be able to find some around the hangar. When you're ready to move on, go activate the clamp release half way between the ladder on the right of the hangar and the fighter on the rotating platform.

As you can see in the cut scene, an Atlas Mech appears from the gaping hole left by the fighter. It is also accompanied by a few troops. Take out the troops before they can get to an unoccupied Atlas Mech on the far left corner of the hangar (alternatively there is an empty mech closer to you on the right side and you can rush to it and take out the enemies easily), then take out the piloted Atlas. Once you're clear, do one more pass for ammo, then head through the hangar doors -- or at least, what's left of them.

M-37 Falcon - On the floor just left of the fiery hole in the wall you can find this grenade-launching Assault Rifle.

Take the door on the left of the fiery hole -- you can open it even though its panel is orange. When the cut scene is over, take the ladder down to the sublevel as EDI suggests. Don't worry, EDI was only joking when she said she likes to see humans on their knees. And besides, there's plenty of room to stand in the sublevel.

Once you're down the ladder, take cover immediately. A few Assault Troopers and a Centurion begin attacking, and once you get past them, a Nemesis awaits further down. Once the area is clear, be sure to grab the Med Kit just beyond the ladder before you head up.

Terminal (Credits) - Next to the Med Kit, just beyond the exit ladder.

Back on the main level, you can learn a little more about your resurrection while EDI hacks through a door.

Look in the rubble behind the console to find Serrice Council Greaves .

Once you're through, head down the hall and drop down through the opening on your right. Vault over some rubble, then head down the ramp on your right.

Down here you encounter the Cerberus Combat Engineers (and their annoying turrets) that EDI warned you about earlier in the mission. Troops are also protected by shield generators and pylons, so take those out if you can to make your fight easier.

Note that Sabotage comes in extremely handy here, since you can hack a turret to take out all the enemies around it. Stay far back from groups of enemies so as not to get flanked, and keep an eye out for the Engineers with large, flat packs on their backs so you can kill them first.

Go up the ladder and use the console while EDI hacks the door again. This time, you learn how EDI was created. In the next room, pick up some ammo and a Med Kit.

PDA (Credits) - On a desk on the right side of the room.

PDA - This PDA in the same area only appears if you imported Jack from Mass Effect 2 and she died because you did not complete Grissom Academy: Emergency Evacuation. It tells of Jack's conversion to Cerberus -- and you'll see more of her shortly.

Exit the room, then turn right. There are two openings ahead of you -- the blue one on the left is the exit, but ignore that for the moment. On your right is a hole exposing the floor below, but you can't climb into it. Go straight, past the two dead bodies and open the door on the right.

In this room you will find a Med Kit on the floor.

Delumcore Overlay - This Body_ArmorBody Armor piece is on a crate next to the far door.

Go through one more door to find another video console. This one shows you some footage of Kai Leng. When you're done, retrace your steps back to the blue hole in the wall (it should be on your right as you head back). Head down.

Assassin Legion - Legion will appear as an enemy if you sold him to Cerberus in Mass Effect 2 and imported a save reflecting this.

Head forward down the catwalk to trigger the next fight. A Phantom appears close to you while reinforcements arrive further down the catwalk. The reinforcements consist of Assault Troopers, more Phantoms, and a Nemesis. Run forward and take down the first Phantom quickly, then get into cover before the Nemesis starts sniping you. When you're clear, proceed down the catwalk and up the ladder.

On the next level, pick up some ammo, then continue your climb. Different level, same group of enemies. Do your thing, then climb up one last time.

Before you go through the door, at the top of the final ladder, head down the catwalk away from the door to find a Med Kit and some ammo.

PDA (Credits) - On the floor, right next to the med kit and the ammo.

Go back to the door and head through. Halfway through the next room, there is another Med Kit and some more ammo on the floor on your left. There's also a Video Console you can activate to learn more about Cerberus troops and the Illusive Man, and some back story on Paul Grayson from the Mass Effect Books.

PDA (Credits) - On the floor, next to the Med Kit and the ammo. Just left of the video console.

Go through the door on the far side of the room, then up the ramp and through the door at the top.

The Kai Leng fight is broken up into several waves. At the very start of the first wave, Leng will grapple with you, and you'll need to mash the MELEE ATTACK button rapidly to throw him off. Immediately have EDI and anyone else with Overload use it on Leng.

Hit him a few more times and his Shields will lock and you can do no more damage. He'll kneel down and summon Troopers. It may seem like you should enter the pit area opposite the Troopers, but if you keep moving around the perimeter of the room you have a better angle to take them out.

Use EDI's decoy and send your squad to opposite sides of the room to spread out the enemy fire.

In this wave, you can reduce Leng's Shields to one bar. Keep using overload and hit him with Disruptor Ammo whenever you can. The Sniper Rifle Concentration Mod is a great asset here since you can slow time and nail him. You can also use melee attacks if your character is built for it.

Leng's deadliest attack is a wave of energy that completely drops your shields. You can dodge this or take cover from it, but if you get hit, get ready to use a Med Kit.

When Leng goes down on one knee again he'll barely recover, but more Troopers will arrive.

It's the third wave of enemies that's a problem: Phantoms are tough to deal with in the trenches, so be sure to head for the sides of the room. They are close-range enemies, so give them some distance between you and your squad. Hopefully you can continue to nail Leng from the sidelines.

Once his shield is gone, use your weapons to whittle away his health bar. One solid shot to the head from a Sniper Rifle can do wonders.

Finally, Leng will fall. In the next cutscene, prepare for a Renegade Interrupt moment to put him down for good and score some points. Avoid this if you are playing 100% Paragon.

Finally, you will have a chance at a Paragon/Renegade Interrupt with the Prothean hologram at the end.